1. Field of the Invention
The present invention relates to a high performance solid catalyst component and an olefin polymerization catalyst using the solid catalyst component. More particularly, the present invention relates to a solid catalyst component derived from diethoxymagnesium, titanium tetrachloride, a phthalic diester in the presence of an alkylbenzene according to a specific procedure and an olefin polymerization catalyst prepared from the solid catalyst component, a specific silicon compound and an organoaluminum compound, the catalyst being capable of exhibiting a high polymerization activity combined with a high stereospecific performance and producing stereoregular olefin polymers in a high yield.
2. Description of the Prior Art
Various kinds of solid catalyst components comprising a dialkoxymagnesium, titanium tetrachloride and an electron donor have been developed and proposed in the polymerization olefins.
In U.S. Pat. No. 4,414,132, for example, there is disclosed the use of a large amount of an organoaluminum compound at the time of polymerization of olefins to enhance activity of such catalysts as well as a process for preparing a catalyst component by bringing a dialkoxymagnesium obtained according to a specific operation into contact with a tetravalent titanium compound in the presence of a halogenated hydrocarbon and an electron donor with the purpose of overcoming drawbacks seen in the prior art processes that stereospecific property of the resultant polymers is deteriorated when hydrogen is added to the polymerization system to control the molecular weight of the produced polymers. According to Example 2 of this patent concretely illustrating the process for preparing the catalyst component, it is analyzed that the catalyst component is obtained by suspending a dialkoxymagnesium in carbon tetrachloride, adding ethyl benzoate and titanium tetrachloride at 75.degree. C., stirring the suspension for 2 hours while maintaining the temperature at 75.degree. C., isolating the resultant solid matter and washing it 5 times with iso-octane, suspending the solid matter in titanium tetrachloride at 80.degree. C., stirring the suspension for 2 hours and then washing the solid matter 5 times with iso-octane. Example 1 of this patent illustrates the use of an olefin polymerization catalyst wherein the solid catalyst component is combined with triethylaluminum.
However, the solid catalyst component prepared according to the process illustrated in U.S. Pat. No. 4,414,132 cannot be said to be satisfactory in its performance with respect to polymerization activity, yield of stereoregular polymers and durability of the activity when used together with other catalyst ingredients for the polymerization of olefins.
With a view to solving such problems seen in the prior art process for the polymerization of olefins, the present inventors developed a new olefin polymerization catalyst in U.S. Pat. No. 4,640,906 and succeeded in furnishing the catalyst with excellent performance for achieving a high level of polymerization activity and durability of such high activity. In this patent, the catalyst is prepared by adding a dialkoxymagnesium and a diester of an aromatic dicarboxylic acid to a halogenated hydrocarbon to prepare a solid catalyst component and combining it with a piperidine derivative and an organoaluminum compound. In this new catalyst, however, there was still a room for improving stereospecific property and bulk density of the resultant polymer.
Under the circumstances, there is still a great demand for developing a new olefin polymerization catalyst which has an extremely enhanced stereospecific performance and affords a high bulk density.